US Secretary of State John Kerry told Russian Foreign Minister Sergei Lavrov on Monday that Washington was watching events in eastern Ukraine with great concern and any further moves by Moscow to destabilize Ukraine - direct or covert - would "incur further costs for Russia." His spokesman called on Russia to publicly disavow activities of “separatists, saboteurs and provocateurs” in Ukraine. She said the two ministers discussed holding direct talks between Ukraine, Russia, the US and the EU in the next 10 days to defuse tensions.